(function (doc,win) {
    var docEl = doc.documentElement,
        resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize',
        recalc = function () {
          var clientWidth = docEl.clientWidth;
          if (!clientWidth) return;
          docEl.style.fontSize = 16 * (clientWidth / 375) +'px';
        };
    if (!doc.addEventListener) return;
    win.addEventListener(resizeEvt,recalc,false);
    doc.addEventListener('DOMContentLoaded',recalc,false);
  })(document,window);